package services

import (
	"context"
	"fmt"

	"veza-backend-api/internal/database"

	"github.com/google/uuid"
	"go.uber.org/zap"
	"golang.org/x/crypto/bcrypt"
)

const passwordHistoryLimit = 5

// PasswordHistoryService manages password history to prevent reuse.
// F014: ORIGIN_FEATURES_REGISTRY.md — stores last 5 password hashes.
type PasswordHistoryService struct {
	db     *database.Database
	logger *zap.Logger
}

// NewPasswordHistoryService creates a new password history service.
func NewPasswordHistoryService(db *database.Database, logger *zap.Logger) *PasswordHistoryService {
	return &PasswordHistoryService{db: db, logger: logger}
}

// CheckReuse compares newPassword against the last 5 stored hashes.
// Returns an error if the password was previously used.
func (s *PasswordHistoryService) CheckReuse(ctx context.Context, userID uuid.UUID, newPassword string) error {
	rows, err := s.db.QueryContext(ctx, `
		SELECT password_hash FROM password_history
		WHERE user_id = $1
		ORDER BY created_at DESC
		LIMIT $2
	`, userID, passwordHistoryLimit)
	if err != nil {
		// Table may not exist yet — not a blocking error
		s.logger.Debug("password_history query failed (table may not exist)", zap.Error(err))
		return nil
	}
	defer rows.Close()

	for rows.Next() {
		var hash string
		if err := rows.Scan(&hash); err != nil {
			continue
		}
		if bcrypt.CompareHashAndPassword([]byte(hash), []byte(newPassword)) == nil {
			return fmt.Errorf("password was recently used — choose a different password")
		}
	}
	return nil
}

// Record stores the current password hash in history after a password change.
// Automatically prunes entries beyond the limit.
func (s *PasswordHistoryService) Record(ctx context.Context, userID uuid.UUID, passwordHash string) error {
	_, err := s.db.ExecContext(ctx, `
		INSERT INTO password_history (id, user_id, password_hash, created_at)
		VALUES ($1, $2, $3, NOW())
	`, uuid.New(), userID, passwordHash)
	if err != nil {
		s.logger.Warn("failed to record password history (table may not exist)", zap.Error(err))
		return nil // non-blocking
	}

	// Prune old entries beyond limit
	_, _ = s.db.ExecContext(ctx, `
		DELETE FROM password_history
		WHERE user_id = $1
		AND id NOT IN (
			SELECT id FROM password_history
			WHERE user_id = $1
			ORDER BY created_at DESC
			LIMIT $2
		)
	`, userID, passwordHistoryLimit)

	return nil
}